This invention relates generally to sprayers and, particularly, to a flow control system for sprayer nozzles.
A typical spraying nozzle comprises a nozzle body, a diaphragm check valve, a nozzle body screen or filter, a nozzle tip and a nozzle cap. The diaphragm check valve shuts off the nozzle at a predetermined pressure. In the case of an agricultural field sprayer, a plurality of nozzles are usually mounted on a spraying bar, towed in the field by a tractor. Alternately, the sprayer could be self propelled. The number of the nozzles on the spraying bar is proportional to the width of the spraying bar.
Various systems have been proposed in the past for reducing or shutting off the fluid flow to a sprayer nozzle body.
Several prior art systems employ solenoid coils with a plunger that are either integral at the nozzle cap in non-standard nozzle bodies and can not be retrofitted to existing sprayer fittings, or are made to adapt to standard nozzle bodies at their check valve location requiring removal of the check and in such location are not filtered by the nozzle body filter. In operation, the coil is energized by a nozzle control system to open the plunger valve.
For agricultural sprayers, the control coils require at least 6 watts per nozzle, hence a large amount of power is drawn from a tractor on larger width units. In most cases, an extra power source is required on the tractor.
In the prior art, the coils are normally in a position with the plunger blocking the fluid path (position which is hereinafter called closed) and must be energized to activate the plunger to displace it to a position allowing fluid flow (position which is hereinafter called open). Therefore if a coil fails or power to the coil is disconnected, the fluid flow from the nozzle body to the tip is affected and there will be a down time in spraying, required to replace or to repair the defective coil.
On many of these prior art systems, the nozzle screen is positioned after the solenoid plunger, thus there is an increased chance that the plunger will become plugged with particles.
Additionally, most of the current nozzle control systems, lack the standard diaphragm check valve, which provides shut off to the nozzle at a predetermined pressure. Therefore, the flow through the nozzles must be controlled solely by the solenoid coils.